Photopolymerisable systems may be used for hologram formation for applications related to security or data storage. Holograms formed with such photopolymerisable systems, e.g. in form of films, are for example volume holograms which may be realised as phase holograms. In these holograms the refractive index may be spatially modulated by an interference pattern of illuminating or exposing light sources—a writing or object beam and a reference beam. The spatially modulated variation in refractive index leads to a diffraction of a reading beam and the information encoded in the hologram may be identified upon the diffracted reading beam (reading).
The larger the gradient of the refractive index between the recorded and the adjacent lesser or non-recorded volumes caused by a corresponding refractive index modulation, the larger is the diffraction efficiency and the greater can be the clarity, brightness and definition of the final hologram.
There still lies a need for advanced materials for hologram formation with high diffraction efficiency, photosensitivity and/or transparency.